1. Field of the Invention
The invention relates in general to elevator systems, and more specifically to hydraulic elevator systems in which the hole required for the hydraulic jack is eliminated, or substantially reduced in depth.
2. Description of the Prior Art
Hydraulic elevator systems conventionally require a hole in the ground for the hydraulic jack which is as deep as the vertical travel dimension of the elevator car. The cost of drilling the hole is substantial. When the hydraulic elevator is to be installed in a low rise building having only a few floors, for use primarily by the handicapped, the cost of drilling the hole may be a relatively large portion of the elevator system cost, because a relatively low cost elevator construction is used for such low rise applications.
Prior art attempts to eliminate the hole have used two hydraulic jacks, disposed on opposite sides of the elevator car. Another prior art arrangement has made the cylinder portion of the hydraulic jack a part of the car structure, adding the weight of the cylinder and hydraulic oil to the weight which must be lifted by the power unit.